What type of 7 pin are you leaving?
The kind where the 4 pin goes around the 7, or the kind where the 4 pin lays in the channel?
If you are leaving the solid 7 where the 4 goes around the 7, then you need more roll because the ball is not losing enough energy before it hits the pins. In order to strike the ball should hit the 1, 2, 5, and 8. If the ball dives in slightly behind the head pin you will hit the 2 too solid and drive it into the side of the 4 and kick it around the 7. If you move to the right 2 boards with your feet and 1 with your eyes, and take a little speed off the ball (try holding it one inch lower) you should kick out the 7, or staying where you are and move your little finger away from your ring finger you should also kick out the 7 if you get the same amount of fingers in the ball. Other options are to change balls to a stronger drilling pattern in a similar coverstock, but who needs to carry all of that gear when you can adjust?
The other variety of 7 pin is called the weak 7 this happens because the ball lost too much energy before it hit the pocket and didn't quite make it to the 17 board before hitting the pins. The pin action is as described as above except the 2 doesn't hit the 4 with enough force to kick it around the 7 so it lays in the gutter.
If this is what is happening to you, you can move the same 2 and 1 adjustment as mentioned above and increase the side rotation by moving your little finger in toward your ring finger and moving your index finger away from your middle finger at setup. This should get the ball into the oil longer and allow enough rotation to be stored so it doesn't burn up on the back end. Or you can change balls to a shiny surface in the same ball or a weaker drilling pattern in the same ball (pin farther from the pap). Any questions respond back.
